Switching rocker arm for internal exhaust gas recirculation with simple latch control

ABSTRACT

A switching rocker arm constructed in accordance to one example of the present disclosure includes an outer arm, an inner arm, a latch, a roller, a first lost motion spring and a second lost motion spring. The outer arm has a first outer side arm, a second outer side arm, an outer arm first end and an outer arm second end. The first outer side arm has a first leg retaining tab. The second outer side arm has a second leg retaining tab. The inner arm is pivotally secured to the outer arm and has a latch bore, a first inner side arm, a second inner side arm, an inner arm first end and an inner arm second end. The inner arm first end has a first finger, a second finer, a first hub and a second hub.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/US2016/040058 filed Jun. 29, 2016, which claims priority to INProvisional Application No. 1943/DEL/2015 filed on Jun. 29, 2015, whichis incorporated by reference in its entirety as if set forth herein.

FIELD

The present disclosure relates generally to switching roller fingerfollowers or rocker arms in internal combustion engines.

BACKGROUND

Variable valve actuation (VVA) technologies have been introduced anddocumented. One VVA device may be a variable valve lift (VVL) system, acylinder deactivation (CDA) system such as that described in U.S. Pat.No. 8,215,275 entitled “Single Lobe Deactivating Rocker Arm” herebyincorporated by reference in its entirety, or other valve actuationsystems. Such mechanisms are developed to improve performance, fueleconomy, and/or reduce emissions of the engine. Several types of the VVArocker arm assemblies include an inner rocker arm within an outer rockerarm that are biased together with torsion springs.

Switching rocker arms allow for control of valve actuation byalternating between latched and unlatched states. A latch, when in alatched position causes both the inner and outer rocker arms to move asa single unit. When unlatched, the rocker arms are allowed to moveindependent of each other. In some circumstances, these arms can engagedifferent cam lobes, such as low-lift lobes, high-lift lobes, andno-lift lobes. Mechanisms are required for switching rocker arm modes ina manner suited for operation of internal combustion engines.

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

SUMMARY

A switching rocker arm constructed in accordance to one example of thepresent disclosure includes an outer arm, an inner arm, a latch, aroller, a first lost motion spring and a second lost motion spring. Theouter arm has a first outer side arm, a second outer side arm, an outerarm first end and an outer arm second end. The first outer side arm hasa first leg retaining tab. The second outer side arm has a second legretaining tab. The inner arm is pivotally secured to the outer arm andhas a latch bore, a first inner side arm, a second inner side arm, aninner arm first end and an inner arm second end. The inner arm first endhas a first finger, a second finer, a first hub and a second hub. Thelatch is slidably connected to the inner arm at the latch bore and isconfigured to selectively extend to engage the outer arm. The roller andbearing are configured on the inner arm. The first and second lostmotion springs are mounted on the respective first and second hubs andare configured to bias the inner arm. The first and second lost motiontorsion springs each have a first leg and a second leg. The first leg ofthe first lost motion spring engages the second leg retaining tab. Thesecond leg of the first lost motion spring engages the second finger.The first leg of the second lost motion spring engages the first legretaining tab. The second leg of the second lost motion torsion springengages the first finger. The first and second fingers of the inner armand the first and second leg retaining tabs are all positionedintermediate (i) the first and second hubs and (ii) the bearing.

According to additional features, the switching rocker arm furthercomprises slider pads configured on the outer arm. The roller and thebearing cooperate to accommodate a main lift and the slider pads areconfigured to accommodate a secondary lift. The latch and the first andsecond torsion springs are positioned at the inner arm first end. Theinner arm further includes a socked arranged at the inner arm first endand a valve pad positioned at the inner arm second end. A pivot axle canrotatably couple the inner arm and the outer arm. The outer arm secondend extends generally above the pivot axle in a direction generallyopposite the valve pad. The socket is configured to receive a ballplunger end of a dual feed hydraulic lash adjuster.

According to other features, the inner arm further comprises a rearstopper that is configured to selectively engage the outer arm. Thefirst and second ends of both of the first and second lost motionsprings are free from engagement with the outer arm first end. The firstand second lost motion torsion springs have respective coil portionsthat are mounted on the respective first and second hubs. The first andsecond leg retaining tabs are each generally in the shape of a hookhaving a respective extension. The first leg of the first lost motionspring is positioned between the first outer side arm and the extensionof the first leg retaining tab. The second leg of the second lost motionspring is positioned between the second outer side arm and the extensionof the second leg retaining tab.

A switching rocker arm constructed in accordance to another example ofthe present disclosure includes an outer arm, an inner arm, a latch, aroller and bearing, a first and second lost motion torsion spring and apivot axle. The inner arm is pivotally secured to the outer arm and hasa latch bore. The inner arm has a first inner side arm, a second innerside arm, an inner arm first end having a socket and an inner arm secondend having a valve pad, the inner arm first end has a first finger, asecond finger, a first hub and a second hub. The latch is slidablyconnected to the inner arm at the latch bore and is configured toselectively extend to engage the outer arm. The roller and bearing areconfigured on the inner arm. The first and second lost motion torsionspring are mounted on respective first and second hubs and areconfigured to bias the inner arm. The first and second lost motiontorsion springs can each have a first leg and a second leg. The firstleg of the first lost motion spring engages the second leg retainingtab. The second leg of the first lost motion spring engages the secondfinger. The first leg of the second lost motion spring engages the firstleg retaining tab. The second leg of the second lost motion torsionspring engages the first finger. The pivot axle rotatably couples theinner arm and the outer arm. The outer arm second end extends generallyabove the pivot axle in a direction generally opposite the valve pad.

According to other features, the first and second fingers of the innerarm and the first and second leg retaining tabs are all positionedintermediate (i) the first and second hubs and (ii) the bearing. Sliderpads are configured on the outer arm. The roller and the bearingcooperate to accommodate a main lift. The slider pads are configured toaccommodate a secondary lift. The latch and the first and second torsionsprings are positioned at the inner arm first end. The socket isconfigured to receive a ball plunger end of a dual feed hydraulic lashadjuster. The inner arm further comprises a rear stopper that isconfigured to selectively engage the outer arm. The first and secondends of both of the first and second lost motion torsion springs arefree from engagement with the outer arm first end.

According to still other features, the first and second lost motiontorsion springs have respective coil portions that are mounted on therespective first and second hubs. The first and second leg retainingtabs are each generally in the shape of a hook having a respectiveextension. The first leg of the lost motion spring is positioned betweenthe first outer side arm and the extension of the first leg retainingtab. The second leg of the second lost motion spring is positionedbetween the second outer side arm and the extension of the second legretaining tab.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a top perspective view of an exemplary switching rocker armconstructed in accordance to one example of the present disclosure;

FIG. 2 is a bottom perspective view of the switching rocker arm of FIG.1;

FIG. 3 is an exploded view of the switching rocker arm of FIG. 1;

FIG. 4 is a side view of the switching rocker arm of FIG. 1;

FIG. 5 is a top view of the switching rocker arm of FIG. 1;

FIG. 6 is a first end view of the switching rocker arm of FIG. 1;

FIG. 7 is a second end view of the switching rocker arm of FIG. 1;

FIG. 8 is a sectional view taken along lines 8-8 of FIG. 5; and

FIG. 9 is a sectional view taken along lines 9-9 of FIG. 5;

DETAILED DESCRIPTION

With reference to FIGS. 1-9, an exemplary switching rocker arm assemblyconstructed in accordance to one example of the present disclosure isshown and generally identified at reference 10. The switching rocker armassembly 10 can be a compact cam-driven single-lobe cylinderdeactivation (CDA-1L) switching rocker arm installed on a piston-driveninternal combustion engine, and actuated with the combination of aduel-feed hydraulic lash adjusters (DFHLA) 12 (FIG. 8) and oil controlvalves (OCV). The switching rocker arm assembly 10 can be engaged by asingle lobe cam. The switching rocker arm assembly 10 can include aninner arm 22 and an outer arm 24. The inner arm 22 generally comprises afirst inner side arm 22 a, a second inner side arm 22 b, an inner armfirst end 22 c and an inner arm second end 22 d. The outer arm 24generally comprises a first outer side arm 24 a, a second outer side arm24 b, an outer arm first end 24 c and an outer arm second end 24 d. Theouter arm 24 further defines a latch bore 25 (FIG. 8).

As will become appreciated from the following discussion, the inner arm22 and the outer arm 24 can be locked together, causing an engine valveto open and allowing the cylinder to operate as it would in a standardvalvetrain. As further shown in FIG. 8, the inner arm 22 can have avalve pad 26 arranged at the inner arm second end 22 d and configured toengage a valve 27. The inner arm 22 can further include a socket 28arranged at the inner arm first end 24 c and configured to receive aball plunger end 29 of the DFHLA 12. The socket 28 and ball plunger end29 can allow rotational freedom of movement in all directions. This canpermit side and possibly asymmetrical loading of the ball plunger end incertain operating modes.

The DFHLA 12 has two oil ports. A lower oil port provides lashcompensation and is fed engine oil similar to a standard HLA. An upperoil port, referred as the switching pressure port, provides the conduitbetween controlled oil pressure from the OCV and a latch assembly 32.The latch assembly 32 includes a latch pin 34 and a biasing member 36.When the latch pin 34 is engaged (extended outwardly along the latchbore 25), the inner arm 22 and the outer arm 24 operate together like astandard rocker arm to open the engine valve. The inner arm 22 includesa rear stopper 38 generally arranged at the inner arm first end 22 cthat is configured to engage the outer arm 24. In the no-lift(unlatched) position, the inner arm 22 and the outer arm 24 can moveindependently to enable cylinder deactivation. Additional description ofthe operation of the DFHLA 12 may be found in commonly owned U.S. Pat.No. 8,915,225 the contents of which are expressly incorporated herein byreference.

A first and second lost motion torsion spring 40 and 42 are incorporatedto bias the position of the inner arm 22 so that it always maintainscontinuous contact with the camshaft lobe. With particular reference toFIG. 3, the first torsion spring 40 has a first leg 40 a, a second leg40 b and a coil portion 40 c. The second torsion spring 42 has a firstleg 42 a, a second leg 42 b and a coil portion 42 c. The outer arm 24has a first leg retaining tab 44 a and a second leg retaining tab 44 b.The first and second leg retaining tabs 44 a, 44 b are each generally inthe shape of a hook having a respective extension 44 c and 44 d. Theinner arm 22 has a first finger 46 a and a second finger 46 b. The firstleg 40 a of the first torsion spring 40 engages the second leg retainingtab 44 b while the second leg 40 b of the first torsion spring engagesthe second finger 46 b. The first leg 42 a of the second torsion spring42 engages the first leg retaining tab 44 a while the second leg 42 b ofthe second torsion spring engages the first finger 46 a. Specifically,the first leg 40 a is positioned between the first outer side arm 24 aand the extension 44 c while the second leg 40 b is positioned betweenthe second outer side arm 24 b and the extension 44 d. The inner armfirst end 22 c includes hubs 48 a and 48 b that receive the respectivecoil portions 42 c and 40 c.

The inner arm 22 and the outer arm 24 are both mounted to a pivot axle50. The pivot axle 50 can be located adjacent to a first end 52 of therocker arm assembly 10, which secures the inner arm 22 to the outer arm24 while also allowing a rotational degree of freedom pivoting about thepivot axle 50 when the rocker arm assembly 10 is in a deactivated state.The latch assembly 32 that selectively couples the inner and outer arms22 and 24 is arranged on an opposite second end 54 of the rocker armassembly 10. In addition to the illustrated example having a separatepivot axle 50 mounted to the outer arm 24 and the inner arm 22, thepivot axle 50 may be integral to the outer arm 24 or to the inner arm22. The rocker arm assembly 10 can include a bearing 60 having a roller62 that is mounted between the first and second inner side arms 22 a and22 b on a bearing axle 64 that, during normal operation of the rockerarm assembly 10 serves to transfer energy from a rotating cam to therocker arm assembly 10.

The configuration of the switching rocker arm assembly 10 provides acompact design. In this regard, the first and second fingers 46 a and 46b of the inner arm 22 as well as the first and second leg retaining tabs44 a and 44 b are positioned intermediate the hubs 48 a, 48 b and thebearing 60 (as best shown in FIG. 5). Moreover, the latch assembly 32and the first and second torsion springs 40, 42 are all located at thesame end (inner arm first end 22 c) of the inner rocker arm 22. Inaddition, the outer arm second end 24 d extends generally above thepivot axle 50 in a direction generally opposite the valve pad ratherthan in front of the inner arm second end 22 d providing furtherpackaging advantages.

The switching rocker arm assembly 10 enables the variability in valvelift by inducing lost motion for one lift profile while transmitting thesecondary lift profile to the valve or vice versa. Generally, thelatching pin or connecting mechanism is tightly controlled to minimizethe effect of the clearance on to the valve lift. However, depending onthe application and purpose of the secondary valve lift, not all designsneed to be tightly controlled. In one such application, where latchclearance to the interfacing arm is not having a wider pronounced effecton the valve. A design that could achieve this configuration has optimalrequirements in the manufacturing process. There are also benefits interms of compactness, cost and better kinematic performance with furtheroptimization of the rocker arm parameters layout.

The rocker arm assembly 10 achieves the main valve lift in the roller 60and the secondary valve lift in slider pads 80 a and 80 b due to theapplication duty cycle. A normally unlatched design is employed toselectively use the secondary valve lift when required per the engineduty cycle. The inner arm 22 houses the bearing 60 and roller 62 whilethe outer arm 24 encompasses the slider pads 80 a and 80 b in the caminterface area. The pivot axle 50 connects both the inner and outer arms22, 24 and is placed over the top of the engine valve. The inner arm 22is mounted over the hydraulic lash adjuster 12 and interfaces with aball socket area of the lash adjuster 12 in a tangential contact (FIG.8).

The latch pin assembly 32 is positioned at the second end 54 of therocker arm assembly 10 at the inner arm first end 22 c extendingoutward, away from the rocker arm assembly 10 for latching. In thisregard, the latch pin assembly 32 is arranged on a common side as thesprings 40 and 42. The configuration provides an improved packaginglayout over prior art configurations. The rocker arm assembly 10includes a compact design for improved kinematics. The rocker armassembly 10 provides reduced mass over valve for improved dynamics. Themain rocker event is over roller design for optimized friction. Theoverall rocker arm packaging is optimized specifically for a givenengine.

The foregoing description of the examples has been provided for purposesof illustration and description. It is not intended to be exhaustive orto limit the disclosure. Individual elements or features of a particularexample are generally not limited to that particular example, but, whereapplicable, are interchangeable and can be used in a selected example,even if not specifically shown or described. The same may also be variedin many ways. Such variations are not to be regarded as a departure fromthe disclosure, and all such modifications are intended to be includedwithin the scope of the disclosure.

What is claimed is:
 1. A switching rocker arm comprising: an outer armhaving a first outer side arm, a second outer side arm, an outer armfirst end and an outer arm second end, the first outer side arm having afirst leg retaining tab, the second outer side arm having a second legretaining tab; an inner arm pivotally secured to the outer arm andhaving a latch bore, the inner arm having a first inner side arm, asecond inner side arm, an inner arm first end and an inner arm secondend, the inner arm first end having a first finger, a second finger, afirst hub and a second hub; a latch slidably connected to the inner armat the latch bore and configured to selectively extend to engage theouter arm; a roller and bearing configured on the inner arm; a first andsecond lost motion torsion spring mounted on the respective first andsecond hubs and configured to bias the inner arm, the first and secondlost motion torsion springs each having a first leg and a second leg,wherein (i) the first leg of the first lost motion spring engages thesecond leg retaining tab and the second leg of the first lost motionspring engages the second finger, and (ii) the first leg of the secondlost motion spring engages the first leg retaining tab and the secondleg of the second lost motion torsion spring engages the first finger;and wherein the first and second fingers of the inner arm and the firstand second leg retaining tabs are all positioned intermediate (i) thefirst and second hubs and (ii) the bearing.
 2. The switching rocker armof claim 1, further comprising slider pads configured on the outer arm,wherein the roller and bearing cooperate to accommodate a main lift andthe slider pads are configured to accommodate a secondary lift.
 3. Theswitching rocker arm of claim 1 wherein the latch and the first andsecond torsion springs are positioned at the inner arm first end.
 4. Theswitching rocker arm of claim 3 wherein the inner arm further includes asocket arranged at the inner arm first end and a valve pad positioned atthe inner arm second end.
 5. The switching rocker arm of claim 4,further comprising a pivot axle that rotatably couples the inner arm andthe outer arm, wherein the outer arm second end extends generally abovethe pivot axle in a direction generally opposite the valve pad.
 6. Theswitching rocker arm of claim 5 wherein the socket is configured toreceive a ball plunger end of a dual feed hydraulic lash adjuster. 7.The switching rocker arm of claim 1 wherein the inner arm furthercomprises a rear stopper that is configured to selectively engage theouter arm.
 8. The switching rocker arm of claim 1 wherein the first andsecond ends of both of the first and second lost motion torsion springsare free from engagement with the outer arm first end.
 9. The switchingrocker arm of claim 1 wherein the first and second lost motion torsionsprings have respective coil portions that are mounted on the respectivefirst and second hubs.
 10. The switching rocker arm of claim 1 whereinthe first and second leg retaining tabs are each generally in the shapeof a hook having a respective extension.
 11. The switching rocker arm ofclaim 10 wherein the first leg of the first lost motion spring ispositioned between the first outer side arm and the extension of thefirst leg retaining tab while the second leg of the second lost motionspring is positioned between the second outer side arm and the extensionof the second leg retaining tab.
 12. A switching rocker arm comprising:an outer arm having a first outer side arm, a second outer side arm, anouter arm first end and an outer arm second end, the first outer sidearm having a first leg retaining tab, the second outer side arm having asecond leg retaining tab; an inner arm pivotally secured to the outerarm and having a latch bore, the inner arm having a first inner sidearm, a second inner side arm, an inner arm first end having a socket andan inner arm second end having a valve pad, the inner arm first endhaving a first finger, a second finger, a first hub and a second hub; alatch slidably connected to the inner arm at the latch bore andconfigured to selectively extend to engage the outer arm; a roller andbearing configured on the inner arm; a first and second lost motiontorsion spring mounted on the respective first and second hubs andconfigured to bias the inner arm, the first and second lost motiontorsion springs each having a first leg and a second leg, wherein (i)the first leg of the first lost motion spring engages the second legretaining tab and the second leg of the first lost motion spring engagesthe second finger, and (ii) the first leg of the second lost motionspring engages the first leg retaining tab and the second leg of thesecond lost motion torsion spring engages the first finger; and a pivotaxle that rotatably couples the inner arm and the outer arm, wherein theouter arm second end extends generally above the pivot axle in adirection generally opposite the valve pad.
 13. The switching rocker armof claim 12 wherein the first and second fingers of the inner arm andthe first and second leg retaining tabs are all positioned intermediate(i) the first and second hubs and (ii) the bearing.
 14. The switchingrocker arm of claim 12, further comprising slider pads configured on theouter arm, wherein the roller and bearing cooperate to accommodate amain lift and the slider pads are configured to accommodate a secondarylift.
 15. The switching rocker arm of claim 12 wherein the latch and thefirst and second torsion springs are positioned at the inner arm firstend.
 16. The switching rocker arm of claim 12 wherein the socket isconfigured to receive a ball plunger end of a dual feed hydraulic lashadjuster.
 17. The switching rocker arm of claim 12 wherein the inner armfurther comprises a rear stopper that is configured to selectivelyengage the outer arm.
 18. The switching rocker arm of claim 12 whereinthe first and second ends of both of the first and second lost motiontorsion springs are free from engagement with the outer arm first end.19. The switching rocker arm of claim 12 wherein the first and secondlost motion torsion springs have respective coil portions that aremounted on the respective first and second hubs.
 20. The switchingrocker arm of claim 12 wherein the first and second leg retaining tabsare each generally in the shape of a hook having a respective extension.21. The switching rocker arm of claim 20 wherein the first leg of thefirst lost motion spring is positioned between the first outer side armand the extension of the first leg retaining tab while the second leg ofthe second lost motion spring is positioned between the second outerside arm and the extension of the second leg retaining tab.